This invention relates to time compensated clock oscillator circuits.
There are many current applications for oscillator circuits that require a high degree of accuracy in their output. An example of one application is a time-of-day clock used in a secure communication system.
In the prior art, the stringent accuracy requirements for an oscillator such as a crystal oscillator or a voltage controlled oscillator, required the selection of precision components, elaborate temperature control schemes, and relatively large quantities of power to drive the circuits. In the case of a portable device, such as a portable radio, that is required to synchronize its transmissions with a precision time-of-day clock, then the aforementioned requirements for building a precision clock oscillator become very prohibitive, not only in the areas of expense, but also in the area of power consumption. The accuracy for a time-of-day clock, that is used to synchronize a field radio that periodically changes frequency, often is in the area of less than one part per million. Thus, it is very difficult to be able to provide an accurate time-of-day clock that is reasonably priced and operates on relatively low power.